**3.4.2 Effect of grammage and wet strength agent on wet tensile strength**

Fig.3-8 showed the effect of grammage and wet strength agent on wet tensile strength when other factors were held at 0 level. Wet tensile strength gradually increased with the increase

Fig. 3-8. Response surface and contour plots for the effects of grammage and wet strength agent on wet tensile strength: beating degree was held at 40SR°,rosin was held at 0.8%, bauxite was held at 4%

strength decreased with the increase of rosin; when the beating degree was higher than 0 level, wet tensile strength increased with the increase of beating degree and rosin, the maximum value occurred when beating degree was held at 30SR°, and rosin was held at 0.4%. This is because added rosin impacted adsorption effect of fibre to wet strength agents, wet tensile strength decreased, but with the continuing increase of beating degree, the fibre sub-wire broom degree further enhanced, the adsorption effect of fibre on wet strength

Fig. 3-7. Response surface and contour plots for the effects of beating degree and rosin on wet tensile strength: grammage was held at 80 g/m2, bauxite was held at 4%, wet strength

Fig.3-8 showed the effect of grammage and wet strength agent on wet tensile strength when other factors were held at 0 level. Wet tensile strength gradually increased with the increase

Fig. 3-8. Response surface and contour plots for the effects of grammage and wet strength agent on wet tensile strength: beating degree was held at 40SR°,rosin was held at 0.8%,

Wet strength agent/%

Wet tensile strength/N

Quantitative/g/m2

**3.4.2 Effect of grammage and wet strength agent on wet tensile strength** 

Rosin **%**

agent was over than the rosin.

agent was held at 1.8%

bauxite was held at 4%

of the grammage and wet strength agent; the maximum occurred when wet strength agent was held at 3%, and grammage was held at 110 g/m2, this is because the number of fibre increased and bonding effect of fibre enhanced, when wet tensile strength increased with the increase of grammage, at the same time, wet strength agent provided cationic charge, fibre strongly adsorbed wet strength agent added because of pulp fibre with anionic charge, so that the wet tensile strength of film increased.
